linux-kernel - Re: [PATCH 2/6] scsi: ufs: ufs-qcom: Add support for UFS device version detection

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Message-ID: <d5ffacca-579e-83c9-148e-1fd3b6ab5aad@quicinc.com>
Date:   Tue, 31 Oct 2023 13:06:09 +0800
From:   Can Guo <quic_cang@...cinc.com>
To:     <neil.armstrong@...aro.org>, <mani@...nel.org>,
        <quic_nguyenb@...cinc.com>, <quic_nitirawa@...cinc.com>,
        <martin.petersen@...cle.com>
CC:     <linux-scsi@...r.kernel.org>, Andy Gross <agross@...nel.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "open list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..." 
        <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] scsi: ufs: ufs-qcom: Add support for UFS device
 version detection

Hi Neil,

On 10/27/2023 8:51 PM, Neil Armstrong wrote:
> On 18/10/2023 16:02, Neil Armstrong wrote:
>> On 11/09/2023 07:59, Can Guo wrote:
>>> From: "Bao D. Nguyen" <quic_nguyenb@...cinc.com>
>>>
>>> Retrieve UFS device version from UFS host controller's spare register
>>> which is populated by bootloader, and use the UFS device version 
>>> together
>>> with host controller's HW version to decide the proper power modes 
>>> which
>>> should be used to configure the UFS PHY.
>>>
>>> Signed-off-by: Bao D. Nguyen <quic_nguyenb@...cinc.com>
>>> Signed-off-by: Can Guo <quic_cang@...cinc.com>
>>> ---
>>>   drivers/ufs/host/ufs-qcom.c | 30 +++++++++++++++++++++++-------
>>>   drivers/ufs/host/ufs-qcom.h |  2 ++
>>>   2 files changed, 25 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>>> index 710f079..8a9d54f 100644
>>> --- a/drivers/ufs/host/ufs-qcom.c
>>> +++ b/drivers/ufs/host/ufs-qcom.c
>>> @@ -1030,7 +1030,7 @@ static void ufs_qcom_advertise_quirks(struct 
>>> ufs_hba *hba)
>>>                   | UFSHCD_QUIRK_BROKEN_PA_RXHSUNTERMCAP);
>>>       }
>>> -    if (host->hw_ver.major > 0x3)
>>> +    if (host->hw_ver.major > 0x3 && host->hw_ver.major < 0x5)
>>>           hba->quirks |= UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
>>>   }
>>> @@ -1038,11 +1038,33 @@ static void 
>>> ufs_qcom_set_pwr_mode_limits(struct ufs_hba *hba)
>>>   {
>>>       struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>>>       struct ufs_dev_params *host_pwr_cap = &host->host_pwr_cap;
>>> +    u32 val, dev_major = 0;
>>>       ufshcd_init_pwr_dev_param(host_pwr_cap);
>>>       /* This driver only supports symmetic gear setting i.e., 
>>> hs_tx_gear == hs_rx_gear */
>>>       host_pwr_cap->hs_tx_gear = host_pwr_cap->hs_rx_gear = 
>>> ufs_qcom_get_hs_gear(hba);
>>> +    host->phy_gear = host_pwr_cap->hs_rx_gear;
>>> +
>>> +    if (host->hw_ver.major < 0x5) {
>>
>> Here you set G2 for < 0x5
>>
>>> +        /*
>>> +         * Power up the PHY using the minimum supported gear 
>>> (UFS_HS_G2).
>>> +         * Switching to max gear will be performed during reinit if 
>>> supported.
>>> +         */
>>> +        host->phy_gear = UFS_HS_G2;
>>> +    } else {
>>
>> So here is for >= 0x5
>>
>>> +        val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
>>> +        dev_major = FIELD_GET(GENMASK(7, 4), val);
>>> +
>>> +        if (host->hw_ver.major == 0x5 && (dev_major >= 0x4 ||
>>> +                          dev_major == 0)) {
>>> +            /* For UFS 4.0 and newer, or dev version is not 
>>> populated */
>>> +            host_pwr_cap->hs_rate = PA_HS_MODE_A;
>>> +        } else if (dev_major < 0x4 && dev_major > 0) {
>>> +            /* For UFS 3.1 and older, apply HS-G4 PHY settings to 
>>> save power */
>>> +            host->phy_gear = UFS_HS_G4;
>>> +        }
>>
>> But behavior of > 0x5 is not clear here, could you clarify it in v2 ?
>
> Now SM8650 is public, could you update it for v2 ?

For HWs whose hw_ver.major is > 0x5, say SM8650, initially phy_gear == 
host_pwr_cap->hs_rx_gear, which is HS_G5.

If a UFS3.x or older UFS device is connected, we overwrite phy_gear as 
HS_G4. I don't see an impact to SM8650.

Please let me know if I misunderstand anything here.


Thanks,

Can Guo.

>
> Thanks,
> Neil
>
>>
>> Thanks,
>> Neil
>